185
FXUS63 KTOP 142343
AFDTOP
Area Forecast Discussion
National Weather Service Topeka KS
543 PM CST Wed Feb 14 2018
...Update to aviation forecast discussion...
.DISCUSSION...(This evening through Wednesday)
Issued at 341 PM CST Wed Feb 14 2018
As of 21Z Wednesday afternoon a western mid-level trough axis was
positioned along the west coast. A plume of Pacific moisture
continues to stream across the central and southern Plains within
the southwesterly flow. Low-level WAA overspread the CWA during
the overnight hours last night, yielding an expansive low-level
stratus deck. Increasing boundary layer mixing has mixed the vast
majority of the stratus deck out, leaving scattered mid and high
level clouds. Temperatures have reached the upper 50s and lower
60s across much of the area with the coolest being across north
central KS, where some snow cover remains.
Tonight: The CWA will remain in the warm sector ahead of the next
cold front. As a result a LLJ near 50kts will overspread the area
after sunset, yielding another round of WAA. Although, cloud
cover looks to remain associated with the Pacific moisture plume
above 10kft. Low temperatures are expected to occur near midnight
with steady to warming temperatures through the night. Weak
isentropic ascent within the 290 and 295K layer could result in a
few sprinkles. That being said, RAP/HRRR/NAM soundings suggest a
stout dry layer within the low levels, which should keep things
dry.
Thursday: The aforementioned surface cold front looks to traverse
the CWA from northwest to southeast throughout the day. By dawn
Thursday morning the front should be through north central KS
where high temperatures will remain in the 50s. Another "spring
like" day is expected for areas along and south of I-70 where H85
temperatures are progged to reach the 10-13C range. Forecast
soundings suggest boundary layer mixing heights approaching H8,
therefore have high temperatures in the upper 60s and lower 70s
for areas south of I-70. Northwest winds will increase behind
front at 15-20 MPH with gusts upwards of 25 MPH. These gusty winds
coupled with RH values in the lower 30s percent will yield high to
perhaps very high fire danger Thursday afternoon for areas mainly
along and southeast I-35/335.
CAA will continue overspread the area Thursday night into Friday.
A dramatic change in temperatures is expected with lows Friday
morning ranging from the mid teens to the mid 20s. Northerly winds
are progged to remain sustained at 15 to 20 MPH with gusts upwards
of 25 to 30 MPH Thursday night and Friday morning. As a result
single digit wind chill values are expected Friday morning. A
decreasing pressure gradient is Friday as a 1037mb surface high
overspreads the central Plains, decreasing wind speeds by Friday
afternoon. A secondary mid-level shortwave trough and associated
surface trough are progged to traverse the area Saturday. Limited
lower tropospheric moisture should yield dry conditions across the
area with the bulk of precipitation remaining south of the CWA.
High temperatures are expected to reach the 50s Saturday
afternoon. Southerly surface flow returns to the central Plains by
Sunday with high temperatures progged to reach the upper 50s to
near 60. Decent agreement amongst the GFS/ECMWF/Canadian regarding
the evolution of the western mid-level trough early next week. All
model solutions have a surface trough traversing the CWA Monday
with at least a few hundred joules of instability ahead of the
front. Therefore have a mention of thunderstorms Monday morning
into the early afternoon. Precipitation may transition to snow
late Monday into Tuesday as temperatures tumble into the teens by
Tuesday morning.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 525 PM CST Wed Feb 14 2018
Mainly a wind forecast with the LLJ still picking up overnight in
the early morning hours. Will also have to watch for some MVFR
cigs that could develop, have added as a SCT group given
uncertainty of the western extent. Winds shift to the northwest
Thursday afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Baerg
LONG TERM...Skow
AVIATION...Baerg